Well cementing method



March 12, 1968 A. L. cANuT WELL CEMENTING METHOD Filed Aug. 16, 1965 ANUT 5 Y C 8 Da l o Ufi, T O T T M N N M? A United States Patent Otltice 3,372,751 Patented Mar. 12, 1968 3,372,751 WELL CEMENTING METHOD Augustin Louis Canut, 3947 Marshall Way, Long Beach, Calif. 90307 Filed Aug. 16, 1965, Ser. No. 479,790 1 Claim. ('Cl. 166-27) ABSTRACT OF THE DISCLOSURE A method of cementing casing Within the annulus of a portion of a well bore by first lowering the casing at the bottom of a pipe string. Cement is then forced down the pipe string and easing until it rises upwardly within the annulus above the casing. Openings are then unblocked between the lower portion of the pipe string and the annulus above the casing while flow through the pipe string below the openings is blocked. Liquid is pumped under pressure through the pipe string and out the openings to break-up the unhardened cement and lift it to the surface. Finally, the upper end of the casing is disconnected from the pipe string below the point where it was blocked and the pipe string is lifted to the surface leaving the well bore unobstructed.

The present invention relates to a method to be employed in the cementing of casing in the bore hole of a Well.

In cementing casing in Well bores various methods and apparatus are conventionally employed. Ordinarily, the cement slurry is introduced into the annulus between the outer wall of the casing and the walls of the bore hole by pumping it from the surface down through the pipe supporting the casing and the casing itself. This cement blows out through the bottom of the casing, from which point the cement flows through the annulus up and around the casing. The cement is then permitted to harden. The portion of the casing adjacent the producing formation is then removed as by milling or cutting, involving considerable time and expense. In addition, the oil producing formation is subject to contamination by the cement filtrate as the latter sets up. Moreover, it sometimes occurs that the casing-supporting pipe string becomes stuck in the well bore by the cement as the latter hardens. The removal of such stuck pipe is time-consuming and costly.

The present invention relates to a novel method of cementing casing within the annulus of a portion of a well bore without the necessity of milling or cutting either the casing or the cement.

It is another object of the present invention to provide a well cementing method which eliminates exposing the producing formation to contamination by the cement filtrate.

A further object of the present invention is to provide a well cementing method which eliminates the danger of the casing-supporting pipe string becoming stuck in the hole as cement hardens.

A more particular object of the present invention is to provide a method of cementing casing within the an nulus of a well bore that includes lowering the casing into the well bore at the bottom of a pipe string, forcing cement down the interior of the pipe string and easing until the cement rises upwardly within the bore annulus to a point above the casing, then providing an opening between the interior of the lower portion of the pipe string and the annulus above the casing while blocking liquid flow below such opening. Before the cement hardens liquid is forced downwardly under pressure through the pipe string and outwardly through the aforementioned opening to thereby break up the unhardened cement in the annulus above the casing, with such broken cement being lifted upwardly through the annulus by the liquid to the earths surface.

These and other objects and advantages of the present invention will become apparent from the following detailed description, when taken in conjunction with the ap pended drawings wherein:

FIGURE 1 is a central vertical view showing a tool that may be utilized in the method of the present invention;

FIGURE 2 is a central vertical sectional view showing a first step in said method;

FIGURE 3 is a view similar to FIGURE 2 showing a second step of said method; and

FIGURE 4 is a view similar to FIGURES 2 ad 3 showing a final step in said method. 7

Referring to the drawings there is shown in a tool T which may be utilized in the method of the present invention. This tool T is adapted to be secured to the lower end of a pipe string P so as to define a downward continuation of the pipe string. The upper end of the pipe string P extends to the earths surface. The lower end of the tool T is removably connected to the upper end of a length of easing C which is to be cemented within the well bore 11. After the casing C has been cemented in the well bore the pipe string P including the tool T is disconnected from the well bore 11 as indicated in FIGURE 4, leaving easing C cemented within the well bore.

More particularly, the tool T includes a generally tubular body, generally designated 12. The body 12 includes an upper section 12a that is threadedly secured at its lower end to a lower body section 12b at a threaded joint 14. The upper end of upper body section 12a is provided with an integral neck 16 formed with internal right-hand threads 18 that fit the conventional external threads formed on the lower end of the drill pipe F.

The lower body portion 1212 has an open lower end. The interior of the lower portion of the body member 1215 is formed with a radially inwardly extending circumferential stop 22. A plurality of ports 24 are formed through the intermediate portion lower body section 1212. The lower end of body section 1% is formed with external left-hand threads 26 that fit the threads 28 formed at the upper end of casing C.

Disposed within the body 12 is a piston member, generally designated 33. The piston member includes a sleeve 32 coaxially with body 12. The inner diameter of the sleeve 32 generally corresponds to the inner diameter of the drill pipe P. The lower portion of the sleeve 32 is formed with a piston 34 that is slidable within the lower body section 12b. The midportion of the piston 34 is formed with a coaxial seat 36. The piston 34 is normally retained in its position shown in FIGURES l and 2 by means of one or more shear pins 4th.

The body 12 is adapted to receive a plug 41 when the latter is'urged downwardly through the pipe string P. The plug 41 has an outside diameter somewhat less than the inside diameter of body neck 16 and sleeve 32.. The lower end of the plug 41 is formed with a pointed nose 41a that seats within the seat 36 of the piston member 35 as indicated particularly in FIGURE 3.

In the operation of the method of the present invention, the aforedescribed tool T is interposed between the upper end of the casing C and the pipe string P. These elements are run into the well bore until the casing C is disposed at the desired elevation. At this time the plug 41 is not in place within the body 12.

Next, cement slurry 42 is pumped downwardly through the pipe string P and flows through tool T and casing C until it rises upwardly through the annulus 44 of the well bore to a point adjacent the upper portion of the 3 tool T, as indicated in FIGURE 2. During this step the ports 24 will be closedby the skirt of piston 34. The well bore and pipe string P are filled with mud 45 above the cement 42 at this time.

Before the cement 42 hardens the plug 41 is dropped through the pipe string P and its nose portion 41a sealingly engages the seat 36 of piston 34. Mud pressure is increased until the downward force applied by the mud 45 against the upwardly-facing surface area of the piston 34 causes the shear pin 40 to break. The piston 34 and plug 41 will then move downwardly until the piston engages the piston stop 22, as indicated in FIGURE 3.

With continued reference to FIGURE 3, such downward movement of the piston member 34 serves to open the ports 24 whereby communication is obtained between the interior of the pipe string P and the annulus 44. The outwardly flowing mud passes through ports 24 and breaks up the unhardened cement adjacent and above the ports. The cement particles 46 will then be lifted upwardly to the earths surface by the mud 45.

When the cement 42. has hardened sufficiently, the pipe string P will be rotated so as to disengage the threads 26 of the tool T from the threads 28 of the casing C. The pipe string and tool T are then withdrawn upwardly through the well bore, as indicated in FIGURE 4 leaving the casing C cemented in place. The tool T may be readied for reuse by unscrewing the upper body section 12a from the lower body section 12b thereof to effect cleaning of the interior of the tool. After such cleaning the shear pin 40 will be replaced.

It should be noted that the aforedescribed method may be utilized in both uncased and cased well bores. It should also be noted that various modifications and changes may be made with respect to the foregoing detailed description without departing from the spirit of the present invention or the scope of the following claim.

I claim: 1. The method of cementing casing within the annulus of a portion of a well bore, comprising:

lowering said easing into said well bore portion at the bottom of a pipe string;

forcing cement down the interior of said pipe string and casing until said cement rises upwardly within the bore annulus from the bottom of said bore portion to a point above said casing;

providing a plurality of circumferential openings between the interior of the lower portion of said pipe string and said annulus immediately above said casplugging said pipe string to liquid iiow below said openings;

"forcing liquid downwardly under pressure through said pipe string, said liquid moving outwardly through said openings to break up the cement in said annulus above said casing, said broken cement being lifted upwardly through said annulus by said liquid; disconnecting the upper end of said casing from said pipe string below the point at which said pipe string was plugged; and lifting said pipe string from said well bore leaving said casing unobstructed.

References Cited UNITED STATES PATENTS 2,646,125 7/1953 Hall 166-154 2,655,216 10/1953 Baker et al. 166154 2,762,440 9/1956 Reed 166-154 2,928,470 3/1960 Baker 166--154 CHARLES E. OCONNELL, Primary Examiner.

DAVID H. BROWN, Examiner. 

